Radiometry
Michael Ljungberg in Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
One of the earliest types of detectors is photographic film, which is an example of a chemical detector. The active material of the film consists of grains of silver bromide (AgBr) embedded in a thin emulsion. This emulsion is placed on a transparent base and covered with a protective coating. Upon irradiation with ionizing radiation (or light, as in conventional photography), a latent image is created. This latent image is then made visible by exposing the film to a chemical (developing) that reduces the exposed silver halides to metallic Ag. In order to make the film insensitive to further exposure, the image is fixed by a chemical that produces soluble salts with Ag ions in the remaining silver halide crystals. These salts are then removed when the film is rinsed.
Food Irradiation: Microbiological, Nutritional, and Functional Assessment
Michael Pöschl, Leo M. L. Nollet in Radionuclide Concentrations in Food and the Environment, 2006
Food irradiation employs an energy form called ionizing radiation, which relays in the absorption of energy by the materials. Ionizing radiation with wavelengths less than 10−10 m, such as γ-rays, x-rays, and electron beams have a higher energy, causing electron transitions and atom ionization, but the energy imparted in the system is not enough to change the nucleus into a radioactive isotope. The mean energy, , imparted by ionizing radiation to an incremental quantity of matter, divided by the mass of that matter, dm, is called the absorbed dose (D), given by Equation 13.1. The definition is given strictly for absorbed dose at a point. In radiation processing, it means the averaged over a finite mass of a given material and is read by a calibrated dosimeter in terms of energy imparted per unit of mass [11]:
Photodynamic Therapy
Henry W. Lim, Nicholas A. Soter in Clinical Photomedicine, 2018
One of the most intriguing applications of photodynamic therapy has been in the therapy of psoriasis. Photofrin II should preferentially accumulate in the vicinity of the abnormal microvasculature of the psoriatic lesion, so significant selectivity should be obtained. Irradiation can lead to vascular and cellular damage as well as to production/release of inflammatory mediators (43–45), so multiple therapeutic processes should be possible. In a preliminary study, McCullough and Weinstein treated patients with varying dosages of Photofrin II (0.5–0.75 mg/kg) and with light sources ranging from UVA to blue–green, to red wavelengths. They found that 3 of 12 patients treated once with 630 nm light had long-term remissions extending for more than 7 weeks (40). The treatment affected the psoriatic plaques but not normal skin. At a 0.5 mg/kg dosage of Photofrin II, no eschar formed on the treated lesion and photosensitivity was minimal (J. McCullough, private communication). Although this work needs replication, the approach may have significant potential.
Induced mutation breeding for qualitative and quantitative traits and varietal development in medicinal and aromatic crops at CSIR-CIMAP, Lucknow (India): past and recent accomplishment
Published in International Journal of Radiation Biology, 2020
Raj K. Lal, Chandan S. Chanotiya, Pankhuri Gupta
There are several approaches to do mutation breeding. Use of radiation is one of them. Irradiation is the method through this a targeted material is exposed to radiation. The exposure originates by the different source. Mostly related to ionizing radiation, that served as distinct aims. The irradiations exclude the exposure to non-ionizing radiation. After discovery by Stadler Lewis at the Missouri university, due to irradiation of seeds resulted in generating worldwide number of varieties of cereals, pulses, and vegetables crops (Ahloowalia et al. 2004). The method by which, seeds or germplasm irradiated by UV, gamma, or X-rays. Irradiation is also used to check the sprouting of onion bulbs, garlic, cereal crops, potato, etc. (Bly 1988). Appropriate irradiation doses are also used for insect/pest control.
Determination of Micropulse Modes with Targeted Damage to the Retinal Pigment Epithelium Using Computer Modeling for the Development of Selective Individual Micropulse Retinal Therapy
Published in Current Eye Research, 2022
Elena V. Ivanova, Pavel L. Volodin, Alexey V. Guskov
The computer simulation of laser impact on eye tissues was performed in two stages. In the first stage, the temperature distribution was calculated as a function of time after exposure with different micropulse power. The corresponding dependence for the center of the spot is presented in Figure 3a. In the second stage, the Arrhenius integral was calculated in order to estimate a concentration of denatured protein. The fraction of native protein at the center of the exposure spot, as a function of penetration depth with respect to the center of the RPE layer, is shown in Figure 3b. Three quantities were introduced to characterize the results of the irradiation process. The quantity, A1, reflects the extent of damage to adjacent structures outside the RPE (harmful effect). The quantities, A2 and A3, are the fractions of denatured and native protein in RPE, respectively. The corresponding regions are shown in red (1), orange (2), and green (3).
Facile green synthesis of bismuth sulfide radiosensitizer via biomineralization of albumin natural molecule for chemoradiation therapy aim
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Hamed Nosrati, Fatemeh Abhari, Jalil Charmi, Mohammad Rahmati, Behrooz Johari, Sedigheh Azizi, Hamed Rezaeejam, Hossein Danafar
Despite many strategies developed for effective treatment of various cancers, global cancer statistics demonstrate that the incidence of cancer met a noticeable increase in through the world. For improving cancer therapy effectively with X-Ray irradiation, high dose irradiation is needed. Unlikely, high dose irradiation can damage normal tissues. High atomic number Z, nanoparticles can desirably enhance the photoelectric, Compton effects and radiation therapy efficacy [1,2]. In addition, by considering nanoparticles power, it is easy to concentrate the high atomic number particles in tumour tissues, and capable to enhance radiation therapy. To date among a lot of studies, colloidal hybrid nanoparticles (HNPs) have been considered as an significant family of multifunctional or enhanced functional nanoparticles [3,4]. HNPs include multiple components in a single nanosized particle. HNPs as novel important properties are attractively considered for biomedical applications. These types of biomaterials have shown abundant application in various biomedical fields, especially, as radiosensitizer [5,6]. Moreover, recent years bismuth compound nanomaterials have attracted huge attention in this field as well. Bismuth is a typical high-Z element with a high X-ray attenuation coefficient (5.74 cm2.kg−1 at 100 keV) [6]. Obviously, the bismuth compounds have the X-ray computed tomography enhancement efficiency [7]. In addition, the possibility of bismuth nanoparticles for in vivo X-ray computed tomography imaging and photothermal therapy/radiotherapy has been demonstrated very lately [6].
Related Knowledge Centers
- Blood Transfusion
- Food Irradiation
- Gamma Ray
- Ionizing Radiation
- Sterilization
- Background Radiation
- Syringe
- X-Ray
- Medical Imaging
- Radiation Therapy